piVA

Raspberry Pi powered Vision Assistant

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This project was aimed to be a little bit different, my intention was to create minimum viable product (MVP) but considering lack of time and errors at hardware planning phase it turned to be more like proof of concept (POC). Despite this, the goal of building this device with the parts I had on hand has been achieved.

Anyway, here is the device that can help blind people perform everyday activities.

Features

• Integration with speech synthesizer (in this case espeak).
• Audio jack for headphones connection.
• Objects detection.
• OCR.
• Standalone power source + usb-c charging.
• Buttons for easier controls.
• Turn on/off switch.

POC Missing Features

• Battery level monitoring.
• 3D printed case, that makes device mobile.

Usage

2 bottom buttons are for navigation between available modules. Top one is for executing currently selected module. Every step (current module change, module executing) is described by speech synthesizer.

Parts

Part Name	Quantity
RaspberryPi Zero 2	1
prototype circuit board	2
sd card	1
RaspberryPi Camera v2	1
5mm ARK connector	7
TP4056 LiPol charger	1
step up converter (2A)	1
on/off switch	2
LiPol bracket	1
RPi GPIO Header	1
20 pin female connector	2
button	3
jack connector	1
270 Ω resistor	2
150 Ω resistor	2
10uF electrolytic capacitor	2
10nF polyester capacitor	2

Assemble

Audio output circuit (I skipped protection diodes) (source: https://learn.adafruit.com/adding-basic-audio-ouput-to-raspberry-pi-zero)

Software

1. flash RPi with raspbian, setup ssh and connectivity
2. add/modify following lines to /boot/config.txt:

For audio output

dtoverlay=audremap,pins_12_13
disable_audio_dither=1

For camera

# Automatically load overlays for detected cameras
#start_x=1
dtoverlay=imx219

3. increase swap

sudo dphys-swapfile swapoff

sudo nano /etc/dphys-swapfile
CONF_SWAPSIZE=1024

sudo dphys-swapfile setup
sudo dphys-swapfile swapon

4. install required system packages

sudo apt install python3-pip espeak ffmpeg tesseract-ocr

5. install required python packages

pip3 install torch==2.1.1 torchvision==0.16.1 --index-url https://download.pytorch.org/whl/cpu --no-cache-dir

pip3 install -r requirements.txt

6. following command should be executed at device startup

python3 main.py

Limitations

• objects detection is slow and lacks precision.
• OCR works good only when text is directly in front of camera.
• there is no case to fit device in and therefore it is not mobile.

Possible Improvements

• replacing built in objects detector with faster and more reliable solution like YOLOv5.
• integrating more advanced ocr solution (filtering, cropping).
• adding battery monitoring system (I was going to use DFRobot I2C Digital Wattmeter).
• creating 3d printed case for device mobility.
• using newer RaspberryPi camera (v3 series).